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pythonarraysnumpymatplotlibjupyter-notebook
Edsel Norwood
Edsel Norwood

Reputation: 159

Plot x-axis with string array as in the same order in original array and not sort it alphabetically in matplotlib

Either Numpy or Matplotlib is changing the order of my np.array and it's conflicting with my plot. It's causing the months to be out of order while the corresponding data to still be in the same order which is causing the plot to look weird:

import matplotlib.pyplot as plt
import numpy as np
import pandas as pd

f = np.array([53, 56, 63, 72, 79, 86, 89, 88, 83, 74, 65, 56])
month = np.array(["Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"])
plt.plot(month, f)

plt.xlabel('Month')
plt.ylabel('Temperature')
plt.title('Average Monthly Temperature in Elizabeth City, NC')
plt.show()

This is what i get as output in JupyterNotebook:

Upvotes: 4

Views: 13404

Answers (2)

AGN Gazer
AGN Gazer

Reputation: 8378

You will need to use MonthLocator and set_major_locator as shown here: formatting timeseries x-axis in pandas/matplotlib

Here is my attempt:

import matplotlib.pyplot as plt
import numpy as np
import datetime
f = np.array([53, 56, 63, 72, 79, 86, 89, 88, 83, 74, 65, 56])

# New stuff:
from matplotlib.dates import MonthLocator, DateFormatter
dates = []
for month in range(1, 13):
    dates.append(datetime.datetime(year=2018, month=month, day=1))
plt.plot(dates, f)
ax = plt.gca()
ax.set_xlim([dates[0], dates[-1]])
ax.xaxis.set_major_locator(MonthLocator())
ax.xaxis.set_major_formatter(DateFormatter('%b'))

plt.xlabel('Month')
plt.ylabel('Temperature')
plt.title('Average Monthly Temperature in Elizabeth City, NC')
plt.show()

Upvotes: 1

kmario23
kmario23

Reputation: 61445

Since month is a string array, plt.plot() command is sorting it alphabetically. So, we have to use the xticks and then plot it like below to get the strings in the same order as it were in the original array month.

In [16]: f = np.array([53, 56, 63, 72, 79, 86, 89, 88, 83, 74, 65, 56])
    ...: month = np.array(["Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"])
    ...: plt.xticks(range(len(f)), month)
    ...: plt.plot(f)

Plot:

plt with months in alphabetical order

Note: For more customized plots refer: pylab date demo

Upvotes: 6

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